Modern jawless fishes (Agnatha) include only two degenerate naked parasites: lampreys and hagfishes.
The earliest vertebrates were heavily armored and were mostly filter-feeders. Jawless fishes can be
classified as Monorhina or Diplorhina, but hagfishes are often separated more strongly from the rest.
- Modern Agnathans:
- Lampreys: Life style and adult anatomy; life cycle.
- Hagfishes
- Vertebrate beginnings:
- Earliest vertebrate fossils
- Conodonts
- Monorhina:
- Cephalaspida (Osteostraci)
- Galeaspida
- Anaspida
- Diplorhina:
- Heterostraci
- Thelodontida
- Classification of agnathans
- Agnathan evolution
Illustrations
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